Wind turbine blades are often formed having an external blade shell formed of a relatively thin-wall composite material. A large number of wind turbine blade designs employ the use of internal shear webs, spars or supports which extend between opposed internal surfaces of such blade shells. Such shear webs act to reinforce the blade structure, and prevent excessive bending or buckling.
Some blade designs use shear webs formed from beam members having I- or C-shaped cross-sections, the members having a main body with load-bearing flanges extending therefrom at opposed ends of the main body.
One method of manufacturing such I- or C-webs is through the provision of a sandwich panel body to which layers of fibre material are applied at the opposed ends in the shape of the desired flanges, the fibre material being infused with a resin and subsequently cured to form rigid flanges.
It is well-known to manufacture such shear webs in a suitably shaped mould structure, wherein a C-web can be manufactured using a relatively simple U-shaped mould, where the sandwich panel body extends between opposed walls of the mould structure, with the flanges formed through the layup of fibre material against the said walls.
Similarly, an I-web can be manufactured using a mould having opposed mould walls, the mould further comprising a central support bounded by flexible support members on either side to define an adjustable channel between the flexible support members and the opposed mould walls. In this situation, the sandwich panel body is arranged on the central support, while the adjustable channel is arranged to receive fibre layers to form the flanges on a first side of the panel body, with the flanges on the second side of the panel body formed by the layup of fibre material against the opposed mould walls. Such I-web moulds have been in use by the Applicant for almost 10 years, while such C-webs are known in the wind turbine industry for a longer period of time.
An example of such manufacturing systems can be seen in International Patent Application Publication No. WO 2013/037466 A1.
However, such systems require the provision of dedicated moulding tables for the formation of such shear webs, which can often be continuous structures in excess of 30-40 meters length, taking up considerable space in a blade factory. Also, the application, infusion and subsequent curing of the fibre layers to form the flanges of the shear webs requires relatively precise alignment and working, resulting in considerable time and operational costs.
Furthermore, in the case of I-web manufacture, the particular flexible profiles used can be unique to the different design of blade and the associated I-web required. This can therefore result in additional manufacturing and setup costs when it is desired to produce I-webs for use in different wind turbine blades.
In addition to the above, shear webs having such resin-infused fibre-based flanges can be an area of interest for the prevention of structural faults and cracks, due to the relatively large forces transferred through said flanges.
It is an object of the invention to provide an alternative system and method for the manufacture of wind turbine blade components, and in particular shear webs, which provides for increased ease of manufacture combined with a reduced risk of structural failure.